import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

//无重复字符的最长子串
public class Test2 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String s = in.next();
        System.out.println(lengthOfLongestSubstring(s));
    }
    public static int lengthOfLongestSubstring(String s) {
        int left = 0,right = 0;
        int flag = 0;
        Map<Character,Integer> map = new HashMap<>();//用来记录字符和字符对应的下标
        //对窗口进行判断

        return flag;
    }
}
